Push Buttons - Embedded System Design - Lecture Slides, Slides of Computer Science

Download Push Buttons - Embedded System Design - Lecture Slides and more Slides Computer Science in PDF only on Docsity! Using push buttons and switches 1 •Push buttons SW2 to SW5 on the Dragon Board are connected to bits 3 to 0 of PortH •When button is pushed, a corresponding bit of Port H is reset. What activity level? •Can be enabled/disabled: •SW_enable(); •Can be checked with C function calls: •SW1_dip(); //returns 8-bit reading of SW1-SW5. Non-blocking •SW2_down(); // true if SW2 is down •SW2_up(); //true if SW2 is up. •Use while ((PTH & 0x01)==0) //to check if the SW5 is being pressed { //…SW5 still pressed } //SW5 released Docsity.com Using switches 2 •There are also 8 DIP switches (sliders) on the Dragon board. •The rightmost 4 switches share the same bits of portH with push buttons. •These switches are intended for use as level-sensitive data inputs to a circuit. •When a switch is in the ON position (away from LCD) it provides a 0 bit on corresponding PORT H bit. •What activity level? •Use: •DDRH=0x00; //Port H inputs • leds_on(~PTH); Docsity.com Seven Segment Display 5 •The Dragon Board has four 7-segment displays. These displays are arranged with the intent of displaying numbers of medium sizes. •Must be enabled/disabled since using same port B of LEDs: •seg7_enable(); •seg7_disable(); •Applying a high logic level to a segment causes it to light up, and applying a low logic level turns it off. •seg7_on(int s, int b); //turns on segment s on 7SEG digit b •What will be the hexadecimal digit coding (assume 0 segment is least significant)? [9 coded as 0x6F] • Use seg7dec(int s, int b); //display hexadecimal value of i on 7SEG digit b Docsity.com LCD controller 6 E R/W RS DB7–DB0 LCD controller communications bus microcontroller 8 CODES I/D = 1 cursor moves left DL = 1 8-bit I/D = 0 cursor moves right DL = 0 4-bit S = 1 with display shift N = 1 2 rows S/C =1 display shift N = 0 1 row S/C = 0 cursor movement F = 1 5x10 dots R/L = 1 shift to right F = 0 5x7 dots R/L = 0 shift to left RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Description 0 0 0 0 0 0 0 0 0 1 Clears all display, return cursor home 0 0 0 0 0 0 0 0 1 * Returns cursor home 0 0 0 0 0 0 0 1 I/D S Sets cursor move direction and/or specifies not to shift display 0 0 0 0 0 0 1 D C B ON/OFF of all display(D), cursor ON/OFF (C), and blink position (B) 0 0 0 0 0 1 S/C R/L * * Move cursor and shifts display 0 0 0 0 1 DL N F * * Sets interface data length, number of display lines, and character font 1 0 WRITE DATA Writes Data •Dragon board has Sanyo DM1623 display of 2x16 characters. •See control signals in pg. 33 and table 7.1 in pg 34 Docsity.com Using LCD 7 •Use: char * msg; msg=“Dragon12-Plus”; lcd_init(); //set configurations set_lcd_addr(0x01);//for first line type_lcd(msg); set_lcd_addr(0x45); //for second line Docsity.com